The present disclosure relates generally to shoulder prostheses, and more particularly to shoulder prostheses configured for use in rotator cuff deficient shoulders.
The rotator cuff is made up of a group of tendons and muscles which includes the deltoid, the supraspinatus, the infraspinatus, the infrascapular, and the smaller round. When massive rupture occurs of the rotator cuff, only the deltoid muscle remains functional which is insufficient to enable proper operation of the shoulder joint. Moreover, improper operation of the shoulder joint due to massive rotator cuff rupture when left untreated will cause erosion or other defects in the subchondral surface of the glenoid. Thus, it is common that a patient who is being treated for a rotator cuff deficiency will also have erosion or other defects of the subchondral surface of the glenoid.
Certain procedures have been used to treat rotator cuff deficient shoulders which have the above described glenoid erosion or defects. For example, the bone of the glenoid may be asymmetrically prepared to create an appropriately configured support to receive a typical metaglene component of a shoulder prosthesis. Asymmetric preparation of bone involves removing more bone from one side of the glenoid in comparison to another in order to create an even support surface for receipt of the metaglene component. In another example, a bone graft is utilized in conjunction with implantation of a standard metaglene component, the bone graft being configured to fill the eroded or defected area of the glenoid so that the implanted metaglene component is appropriately supported. Yet another example involves interposition shoulder arthroplasty in which new tissue is placed between the damaged surfaces of the joint. In interposition shoulder arthroplasty, a tissue-type graft is sutured over the eroded or defected area of the glenoid so as to ease the pain of the damaged joint while allowing the shoulder joint to retain some function. Interposition shoulder arthroplasty is typically a temporary solution to shoulder joint deficiency, and standard shoulder reconstruction will typically follow after several months.
Each of these treatments has significant drawbacks. For example, implanting a metaglene component in bone that has been asymmetrically prepared results in healthy bone stock being sacrificed. Use of a bone graft in conjunction with a metaglene component may have complications due to graft non-union and not all patients have adequate bone stock available for such a procedure. Interposition shoulder arthroplasty tends to be a short term solution that masks the shoulder joint deficiency, only to be followed some time later by more invasive conventional shoulder reconstruction in which humeral and glenoid components are implanted. This two step process results in more risk and inconvenience to the patient since two surgical procedures are involved.
What is needed therefore is an improved shoulder prosthesis for use in a rotator cuff deficient shoulder that involves glenoid erosion or defects. What is also needed is a shoulder prosthesis for use in a rotator cuff deficient shoulder that involves glenoid erosion or defects that conserves healthy bone stock. What is further needed is a shoulder prosthesis for use in a rotator cuff deficient shoulder that involves glenoid erosion or defects that does not necessitate a bone graft to be implanted in conjunction with the shoulder prosthesis. What is additionally needed is a shoulder prosthesis for use in a rotator cuff deficient shoulder that involves glenoid erosion or defects which does not promote a two stage surgical approach to restoring proper function of the shoulder joint.